The stream to print the results to. If NULL, then output is
stdout again.

filename

The file to print the results to. If NULL, then output is stdout
again.

Remarks

The set_outputstream, set_outputfile functions define the output
when lp_solve has something to report.
This is done at the same time as something is reported via put_logfunc.
The default reporting output is screen (stdout). If set_outputstream is called to change output to another
stream, then be aware that the stream is not closed automatically when delete_lp
is called. Output must be set again to stdout (or NULL) to close this handle or the handle must
be closed by the application via a call to fclose afterwards. This allows the application to still
print to the stream even after the lp structure is cleaned up. If set_outputfile is called to change output
to the specified file, then the file is automatically closed when delete_lp is called.
Note that this was not the case in previous versions of lp_solve.